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InterlockedCompareExchange function

Performs an atomic compare-and-exchange operation on the specified values. The function compares two specified 32-bit values and exchanges with another 32-bit value based on the outcome of the comparison.

Parameters

Return value

The function returns the initial value of the Destination parameter.

Remarks

The
function compares the Destination value with the Comparand value. If the Destination value is equal to the Comparand value, the Exchange value is stored in the address specified by Destination. Otherwise, no operation is performed.

The parameters for this function must be aligned on a 32-bit boundary; otherwise, the function will behave unpredictably on multiprocessor x86 systems and any non-x86 systems. See _aligned_malloc.

The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. This function is atomic with respect to calls to other interlocked functions.

This function is implemented using a compiler intrinsic where possible. For more information, see the WinBase.h header file and _InterlockedCompareExchange.

This function generates a full memory barrier (or fence) to ensure that memory operations are completed in order.